Brake system



E. P. SEXTON Marli 21, 1944.

BRAKE SYSTEM Filed Jan. 6} 1942 2 Sheets-Sheet 1 wMOFUD INVENTOR EVERETT FIBEXTON ATTORNEY INVENTOR EVERETT F. SEXTON H 1 ATTORNEY .E. P. SEXTON I A! If...

Filed Jan: 6, 1942 March 21, 1944,

Patented Mar. 21, 1944 UN lTiED STAT ES PAT EN T OFFICE 2,344,902.

BRAKE SYSTEM Everett P. Sexton, Jeannette, Pa., assignor to The 'Westinghouse Air Brake Company, Wilmerding, Pa, a corporation of Pennsylvania Application January 6, 1942, Serial No. 25,725

(01. 303-20) This inventionrelates to fluid pressure brakes 24 Claims.

and more particularly :to an electrically controlled fluid pressure :brake adapted for use on railway vehicles.

The principal object of the :invention is to provide a novel electric-hydraulic yehicle brake controlling means.

Another object of the invention is to provide an electrically controlled hydraulic brake system provided with a conductors switchdevice adapted to be manuallyoperated -'to effect anapplication of the brakes, atripswitch device {adapted to be automatically operated from :the trackway to effect an application of the -brakes, .and safety apparatus which includes meansfor .efiecting an application of the brakes :uponeither the incapacitation of an operator, the 'loss of electric energy or a break-in-two of the train.

A further object of the invention is to provide an electrically controlled hydraulic brake con.- trolling apparatus "in which the electric controlling circuit is normally .closed so as to insure that an application of 'the'brakes will be effected upon a failure of the source of :electrical energy,

a break-in-two of thetrain and thereby thetrain wires of the control circuit, the 'incapacitation of the operator, the operation of a conductors switch to open the circuit, or the operation of a track controlled trip switch to'openthe circuit.

A still further object of the invention is to provide a novel electrically controlled brake controlling valve device.

Other objects and advantages will appear *in the following more detailed description of the -invention.

In the acompanying drawings, Fig. 1 is a die,- grammatic view, partly in section, of an electrically controlled hydraulic braking system embodying my invention.

Fig. 2 is a diagrammatic sectional view of the control valve device shown in outline in Fig. 1, the several parts .of the device being shown in release or running position.

In Fig. .1 .of the drawings the equipment for the locomotive or leading vehicle of a train and .two trailing vehicles of the train have been shown. Itwill be understood that with the exception of the hereinafter described source of electric energy, operators controlswitch device, the safety control or deadmanfs switch device and the trip switch device on the locomotive the brake equipment on all of the trailing vehicles in the train may be similar to that on thelocomotive or leading vehicle.

The locomotive orleading car-equipmentx ifa as the invention is concerned, may compltise as shown Fig. l .of the drawings, an electrically controlled brake controlling valve device ,I, a pump.2, an .operators manually controlled ,brake controlling switch device ,3, a tripswiteh device .4, alconductofls switchdevice ,5 a safety control switch device '6, a, brake cylinder device 9 and a source of electrical energy which is illustrated in the present embodiment .of the invention as a storage battery 1.0.

The brake equipment .on each trailing car of t the train, in-so far as the invention isconcerned,

comprises an electrically controlled brake controlling valve ;device I, ,a pump Z, :aconductbrs switch device 5 and a brakecylinderzdevice :9, all of which are identical with the corresponding devices indicated by similar reference numerals on the leading vehicle.

The pump 2, which may be of any standard construction, is driven from the vehicle axle in any suitable mannerand isconnectedto the electrically controlled brake controlling valve device 1|, bymeans of a'pump discharge pipe H through which the pump forces liquid to the valve device I. The liquid supply to the pump is by wayvof .an inlet pipe i2 leading from the valvedevice l.

The brake cylinder device '9 is of the usual well known construction which is operative, by the .force of "liquid supplied thereto by the-pump, for effecting an application of the brakes and which operates upon a decrease in the force of the 'liquid'therein for effecting a. release of the brakes. This brake cylinder is connected to the electrically controlled brake controlling valve device i by means of a pipe t3 through which the liquid is adapted to be supplied to .and released from the'brake cylinder.

The electrically controlled brake controlling valve device I for controlling the supply of liquid to and the displacement of liquid from the brake cylinder device 9, may, as best shown in Fig. 2 of the drawings, comprise a brake controlling portion l4, a solenoid portion l5 and a control lever l6 operatively associated with both portions.

The-brake controlling portion M may comprise a sectional casing having a substantially U- shaped body section l1, cap section 18 and I9 and an endsection 20, which are secured to the body section in any desired manner. The cap section I8 is clamped to the inner surface of one leg of the "body section and the cap section 19 :is clamped to the inner surface of the other leg. The cap sections are axially aligned with each other and are spaced apart for accommodating the control lever l6 as will hereinafter fully appear. The end section 2|] is clamped to the outer end surface of the leg of th body section to which the cap section |9 is clamped.

Clamped between the body section H and the cap I8 is a flexible diaphragm 2|. At one side of this diaphragm there is a chamber. 22 which is in constant open communication with a passage 23. At the opposite side of the diaphragm there is a chamber 24 which is open to the atmosphere through a central opening 25 provided in the cap |8.

Contained in chamber 22 and abutting one face of the diaphragm 2| is a diaphragm follower 26. Contained in chamber 24 and abutting the opposite face of the diaphragm 2| is a diaphragm follower 21. The followers 25 and 21 are secured together by means of a stem 28 which is carried by the follower 26 and which extends through the diaphragm and has screwthreaded engagement with the follower 21. The diaphragm follower 21 is provided with a stem 29 which extends through the central opening 25 in the cap 8 to the exterior of the casing for a purpose hereinafter described, there being sufficient clearance between the stem and the casing to ensure an always open communication between the chamber 24 and the atmosphere.

Axially aligned with the chamber 22 and disposed at the left thereof, as viewed in the drawings, is a bore 30 which is closed at its outer end by means of a plug 3| having screwthreaded engagement with the casing. This bore is connected to chamber 22 by way of a central passage 32 and is also in constant open communication with a passage 33. Contained in this bore is a valve 34 for controlling communication through the central passage 32. This valve is adapted to have seating engagement with a valve seat 35 which surrounds the passage 32 and is provided with a fluted stem 36 which extends through the central passage into the chamber 22, the end of which stem is spaced away from the follower 26 when the valve 34 is in seating engagement with its seat 35.

Also contained in the bore 38 and interposed between and operatively engaging the plug 3| and the valve 34 is a spring 31 which tends, at all times, to urge the valve into seating engagement with its seat 35.

Clamped between the body section I! and the cap I9 is a flexible diaphragm 38. At one side of the diaphragm is a'chamber 39 which is open to the atmosphere through a central opening 48 provided in the cap portion l9. At the opposite side of the diaphragm is a chamber 4| which is in constant open communication with a passage 42 which passage is connected to the passage 23 and pipe l2.

Contained in chamber 39 and abutting one face of the diaphragm 38 is a diaphragm follower 43. Contained in chamber 4| and abutting the opposite face of thediaphragm' 38 is'a diaphragm follower 44. The followers 43 and 44 are secured together by means of a stem 45 which is carried by the follower 44 and which extends through the diaphragm and has screwthreaded engagement with the follower 43. The diaphragm follower 43 is provided with a stem 45 which extends through the central opening 40 in the cap L3 to th exterior of the casing for a purpose hereinafter described, there being suflicient clearance between the stem and the casing to ensure always open communication between the chamber 39 and the atmosphere.

'Axtally aligned with the chamber 4| and disposed at the right hand side thereof, as viewed in the drawings, is a diaphragm 41, which is clamped between the U-shaped casing section I! and the end section 20. Formed at one side of the diaphragm 41 is a chamber 48 which is in constant open communication with a passage 49 which is connected to passage 33 and pump discharge pipe At the opposite side of the diaphragm is a chamber 50 which is open to the chamber 4| through a central opening 5|.

Contained in chamber 58 is a follower 52 which is secured to the diaphragm 41 by means of a follower nut 53 which nut has screwthreaded connection with, the follower. Clamped to the follower 52 by means of a follower stem 54 having screwthreaded connection with the follower is a valve 55 which is movable into and out of engagement with an annular seat rib 55 for controlling communication through the central opening 5|, the seat rib' being formed on the casing and encircling the opening. The stem 54 extends through opening 5| into chamber 4| where it is adapted to be engaged by the follower 44. There is however normally a slight clearance between the end of the stem and the follower 44 to insure the proper seating of the valve 55.

The chamber 48 is adapted to be connected to the chamber 58 by way of a passage 59 which is formed in the diaphragm follower nut 53 and the diaphragm follower 52 which is controlled by a valve -82 carried .by a plunger 5| slidably mounted in a wall 60 of the end casing 28. This 'valve is adapted to engage with a valve seat 65 carried by the diaphragm follower nut 53 in axial alignment with the valve and encircling the passage 59 for closing th communication through the passage. The plunger, at its other end, is provided with a head 66 which is adapted to engage one side of the wall 88 to limit movement of the plunger toward the diaphragm nut. Interposed between and operatively engaging the head 58 and a cap -61 is a spring 68 which at all times .tends to move the plunger to the position in which .it is shown in Fig. 2 of the drawings.

The end section 20 of the casing is provided with a chamber 10 which is connected to passages 23 and 33. Contained in this chamber is a ball check valve II which prevents backfiow of liquid from the chamber to the passage 33 and which is normally biased toward its seated or passage closing position by means of a spring 12, thus normally cutting oif communication from .the passage 33 to the chamber 10 and the passage 23.

The control arm or lever it extends between the ends of the follower stems 29 and 4B and at one end is pivotally mounted on a pin 13 mounted in lugs provided on the central portion of the U-shaped body section ll of the casing. The other end of the arm or lever is operatively connected by means of a pin 14 to the right hand end of an operating plunger15 of the solenoid portion l5. The lever or arm intermediate its ends is provided on one side with a boss 16 for engagement with the diaphragm follower stem 29 and is provided on the other side with a similar boss for engagement with the diaphragm follower stem 45.

The solenoid portion l5 for effecting the operation of the lever 15 comprises in addition to the plunger 14, a release coil or winding 8|, an application coil or winding 82 and a spring 83. The spring 83 is interposed between and operatively engages the lefthand end of the plunger 15 and a bracket 84 carried by the vehicle. This spring tends to at all times urge the plunger in a direction toward the right hand for a purpose presently described.

The plunger is made of soft iron and is encircled by the windings or coils BI and 82, the flow of current from the storage battery 10 through winding or coil 8| inone direction causing the plunger to move toward the left "hand against the opposite action of the spring 83 as viewed in the drawings, and the now of current from the storage battery through the coil or winding '82 in the opposite direction causing the plunger tomove toward the right hand.

The electric circuit for controlling the release winding or coil 8! is a low wattagecircuitof the normally closed type which is under the control of the operators brake controlling switch device 3, theconductors switch 5, a break-in two-of the train, the trip switch device 4 and the safety control or deadmans switch device 15. i

The electric circuit for controlling the application winding or coil 82 is of the normallycpen type which is controlled only by operation of the operators brake controlling switch device 3.

The above mentioned circuits comprise a plurality of train line wires or conductors which LEX- tend throughout the length of 'the train, there being suitable couplings between the adjacent ends of the vehicle and the Wires. These train wires or conductors, for the purpose of clarity, are designated as conductors wire 85, release wire 86, return wire 8 and application wire 88.

It will "be noted that one end of the release coil or winding Bl oneac'h vehicle of the train'is connected to the release wire 86, and that the other end of the coilor winding is connected to the return wire 81, the return wire being con- -nected to the negative terminal of the storage battery 10 on the locomotive or leading vehicle of the train. One end 01? the coil :or winding 32 on each vehicle of the train is connected to the application wire 86 and theother end of the coil :or winding is connected to the return wire 87.

The conductors WireEE and the release wire 85 are connected together at the rear end of the last vehicle of the train by means of a readily attachable connector 9%.

The operators manually controlled switch :device 3 comprises a foctpedal El which is pivotally mounted on a rigidly fixed bracket 92. l by and suitably insulated from the pedal .9! IS a contact plate 93 which is adapted to moved into and out of engagement with a pairof contact members, such for example as, plungers 84 and 95. connected by means of a conductor :96 to one of the stationary contacts 9'! of the safety control. switch device 6. The other contact 191 of the safety control switch device is connected to the positive terminal of the storage battery ill by way of a conductor 96, a resistance element 99 and a conductor I 68. The contact memberpr plunger 65 is connected to the conductors wire The switch device 3 further comprises ;a rheostat l'lH which controls the supply current from the storage battery It to the appllcation'wn'e 3d. The rheostatcomprises a wlndingor co l I112 con: nected at one end to the application w re .88 and is provided intermediate its length with a .pllu; rality of stationarycnntacts 4%, int, 'ldfi and ale which are adapted to beengaged successively by a movable contact member 40.1;carr1ed by and insulated from an arm W8 which formsiazparti'oi the foot pedal 9i.

Carried v The contact member or plunger 1% is The contact member :llll is depressible button having secured thereto and insulated therefrom a bridging contact H2,

adapted when urged upwardly by a spring I I3 to bridge two stationary contacts N4 the switch normally being-maintained in its bridgingor circuit closing position.

The-trip switch device "4 is also interposed in the .conductors wire and may comprise'a'pivotally mounted contact arm I I5 normally adapted to bridge two spring contacts H5. The contactarm ll5'is adapted to engage a ramp H7 located along the track for rocking the contact arm forautomatically opening the circuit between the "two contacts 1| 1-5.

Operation With the partsof the apparatus in.the release or running position, .as shown in the drawings the .trip switch device 4 :and the conductors switch device .5, one of-which is provided on each vehicle, .will be maintained intheir circuit closing position and .the safety control or deadmans switch device 16 will be maintained in its circuit closing position by manual pressure applied by the operator. Withthese switch devices thus positionedthe releasecoil or winding ill of each controlling valve device will be energized through a circuit including the positive terminal of "the storage battery 1,0, conductor mil, resistance element .9.9 .-c0nductor 98, thesafety control or dead mans switch 6, conductor 96, plunger 94 of the manually controlled switch device 3, contact plate 93, plunger 95; conductoris wire 85, conductors switch devices5, rear couplingconnector '99, the release wire-86, the winding orcoil :81 oneach vehicle, the return wire -8'! and the grounded negative terminal of the storage battery It. Upon energization of the .coil or winding Bl of each brake controlling valve device I the operating plunger 15 and thereby the connected arm or lever N3 of the device are caused to be moved against .the opposing action of the spring 83 to their release or normal position in which they are shown in-the drawings.

Since the boss l6 :on the lever I6 engages the diaphragm follower stem 29, :rnovement of the lever to this position 'unseats the valve 34 against the opposing action of the spring 131 Vthroughthe medium of the diaphragm follower 26, diaphragm 21 and diaphragm follower 2 1, the :follower 2'! engaging the end of the fluted stem 35 and moving the valve 34 away from its :seat 35.

in the position in which they are shown, thus maintaining the valve 55 in seating engagement with the annular seat rib 56.

It should here be mentioned that with the exception of the atmosphere diaphragm chambers 24 and 39 all of the other chambers, passages, pipes, pump and brake cylinder are initially filled with the operating oil for controlling the brakes.

When the vehicle is traveling over the road, the oil pump 2 on each vehicle is driven to displace oil in the systems. Since the hydraulic system is identical on each vehicle the following description of the operation will for simplicity be limited to one system. The oil pump as it continues to operate causes oil to circulate from the pump through pipe I I, passage 33, bore 30, past the open valve 34, chamber 22, passage 23 and pipe I2 to the pump. Since there is no restriction or opposition to this flow of liquid'there will be no pressure built up in the circulating system so that there will be no flow of liquid from the passage 33 through pipe I3 to the brake cylinder or past the check valve 1|, nor will there be any fiow of liquid through passage 49 to the chambers 48 and 50 or through passage 42 to the chamber 4I. From this it will be understood that since the oil circulates freely through the circuit just traced the brakes will remain in their normal po sition as shown.

When it is desired to effect a service application of the brakes, the foot pedal 9! is depressed a distance corresponding to the desired degree of application of the brakes, that is to say the greater the movement of the pedal the greater will be the degree of application obtained.

The foot pedal as it is depressed rocks in a counter-clockwise direction about its pivotal connection with the bracket 92 causing the contact plater93 to move in a direction away from the plungers 94 and 95 and causing the contact I01 to move into engagement with the stationary contact I03. As the pedal and thereby the contact plate 93 is thus moved, the plungers 94 and 95 will move outwardly under the influence: of springs I20 and I2I, respectively.

At substantially the same time or immediately after the contact I01 engages the contact E03, stop collars on the plungers 94 and 95 engage the plunger casing and bring the plungers to a stop and as a result continued movement of the pedal will cause the contact plate 93 to move out of engagement with the plungers 94 and 95, and thus open the circuit through the conductors wire 85 and thereby through the release wire 86 and coils 8|.

When the contact I01 engages the contact I03 the normally open circuit through the application coil or winding 82 of the controlling valve device on each vehicle of the train is closed.

The circuit just closed through which current is supplied for energizing the winding or coil $2 of the controlling valve device I on each vehicle of the train comprises the conductor I which leads from the positive terminal of the storage battery I0, conductor I09, contact I01, contact I03, resistance coil I02, application wire 88, coil or winding 82 of each controlling valve device, return wire 81 and the grounded negative terminal of the storage battery I0. It will be understood that the amount of current supplied to the winding or coil 82 will be determined by the position of the pedal 9| for as the contact I01 is moved in a counter-clockwise direction progressively-into engagement with the contacts I03 to I06 the resistance I02, which is included in the circuit for the coil or winding 82, is decreased, thus the amount of current flowing to the coil 82 is increased.

Energization of the winding or coil 82 of each controlling valve device I will cause the plunger 14 of the solenoid portion I5 and thereby the attached lever I6 to move to its extreme right hand position, such movement being assisted by the spring 83 at the beginning of its travel. Initial movement of the plunger 15 in this direction is not delayed even though the coil or winding 8| which is energized through a low wattage circuit should be maintained energized for a short interval of time after the coil 82 is energized, energization of the coil 82 will overcome the opposing force of the coil 8|.

As the lever I6 is being moved toward this position, the spring 31 acts to seat the valve 34 on its seat 35, thus closing communication between the bore 30 and chamber 22 and thereby interrupting the circulation of liquid from the outlet to the inlet of the pump. After the valve is seated the diaphragm 2I and associated followers, due to the inherent resiliency of the dia phragm, move toward the right relative to the valve 34 until the follower 21 engages the cap portion I8 and brings the diaphragm assemblage to a stop. When this occurs the diaphragm follower 26 will be out of engagement with the fluted stem 36 of the valve. This insures the proper seating of the valve. When the diaphragm assemblage is brought to a stop the lever I5 will be in its midway position in which the lever engages the end of the follower stem 45.

As the lever It continues to move in a direction toward the right hand the diaphragm 36 is caused to flex in the same direction and thereby moves the diaphragm follower 44 into engagement with the end of the stem 54 and forces the valve out of engagement with its seat rib- 56. As this movement is continued the valve seat is moved into engagement with the valve 62, thereby cutting off communication between chambers 48 and 50 by way of passage 59. After the valve seat 65 engages the valve 62, the continued movement of the follower nut 53 causes the plunger 6| to be moved against the opposing pressure of the spring 68, the spring acting to maintain the valve 62 in close contact with the valve seat 65.

With the communication between bore 30 and chamber 22 in each of the brake controlling valve devices cut off the circulation of oil from the pump discharge pipe II to the pump supply or inlet pipe I2 by-way of passages 33 and 23 is stopped, as hereinbefore described. Under these conditions the oil discharged by the pump to the pump discharge pipe II and connected passage 49 will flow to the chamber 48 in the brake controlling valve device I and also to the brake cylinder 9 by way of connected passage 33 and passage and pipe I3. As the pressure of oil rises, the brake cylinder 9 on each vehicle of the train will operate to effect an application of the brakes. At the same time the pressure in chamber 48 of each controlling valve device is being built up and will continue to build up until the pressure of liquid in this chamber and consequently in the brake cylinder has been increased to a degree slightly exceeding the opposing force of the plunger 15 transmitted through the lever I5. When this occurs the pressure of the liquid in the chamber 48 and acting on one face of the diaphragm 41 and on the diaphragm nut 53 causes the diaphragm to move in a direction. toward the left hand, the valve 62 being main tained in engagement with its seat 65 by spring 68 until the plunger 6| is brought to a stop by the engagement of the head 66 thereof with the wall 60.

If the vehicle is still in motion when the plunger Si is brought to a stop the further increase in the pressure of liquid in chamber 48 causesthe diaphragm 41 to act to move the valve seat 65 out of engagement with the valve 62. Liquid now flows from chamber 48 through passage 59 to chamber 50 and from thence past the unseated valve 55 to the pump inlet by way of chamber 41, passage 42 and pipe 12. The distance between the valve and its seat will be such that it will permit liquid to flow to chamber 50 and thereby to the pump inlet at arate corresponding to the rateof flow of liquid from the pump to the chamber 48, so that the pressure in chamber 48 will be maintained at that called for by the setting of the brake switch device 3.

When the vehicle comes to a stop, the pump will of course cease-to functiomand since no further increase in pressure in the liquid in chamber 48 is possible the plunger will, when the pressure in chamber 48 has reduced slightly, cause the diaphragm assemblage to operate to mov the valve seat 65 into seating engagement with the valve 6|, thus the brakes will be maintainedapplied. i

From the foregoing description it will be under-- stood that if it is desired to increase the brake cylinder pressure while the vehicle is in mo-tion,. the pedal 9| may beclepressed further in its application zone thereby further rotating the arm I08 in a counterclockwise direction to decrease the amount of resistance in the circuit and thus increase the amount of current flowing to theapplication coil or Winding 82. Upon such an increase in the current supply to'the coil or winding 82 the plunger 15 is caused to exert increased force on the lever I3 and thereby on the diaphragm 47, thus it will require a higher pump dis charge pressure and consequently a-higher brake cylinder pressure to balance the opposing force of the lever l6.

The-brakes may be fully releasedby permitting the foot pedal ill to return to release position, as shown in the drawings, in which position the contact I09 is moved out of engagement with the contact I03 thus opening the circuit from the storage battery Ill to the application coil or winding 82 of each controlling valve device I throughout the train, thus deenergizing the application coil or winding on each vehicle. At the same time or slightly before this circuit is opened the contact plate 93 will be moved into engagement with the plungers 94 and 95 so that the release coil or winding 8! will be energized by way of the. circuit hereinbefore traced.

Upon deenergization of coil or winding 82 and energization of coil or winding 8| the plunger 15' and attached lever 56 willbe moved to the position in which they are shown in the drawings. The lever 16 as it thus moves forcing the valve 34 out of. engagement with its seat 35 so that the pump discharge pipe and connected chamber 48 andbralie cylinders will be relieved of oil pressure in a manner hereinbefore described, thus permitting the. brake cylinder 9 on each vehicle to effect a r ease of the brakes.

lThe rel'e; e of the brakes may be graduated off instead of fully releasing same, by permitting a partial movement of" the pedal 9! toward release position, soas to reduce the degree of energization of the application coil or winding 82; This results in a' reduction inthe force exerted by the plunger 15 and thereby determines the degree of reduction in brake cylinder pressure called-for by the brake control switch device 3. y

As hereinbefore mentioned the circuit through which current is supplied fom the battery Hlfor energizing the release coil or winding 8| of the controlling Valve device is of the closed type. Therefore, when this circuit is rendered ineffective either by loss of current supply,operation of the safety control switch device 6 operation of a conductors switch device 5, operation of the trip switch device 4, or in caseof a break-in-two of the train, the release coil or winding is: deenergized and full braking forces will-be effective as will now be described.

When the circuit leading to the release coil or winding 8| fails or is opened.- in anyof the above enumerated ways, the spring 83 will move the plunger l5 and attached lever Hi to a position in which the lever It will assume its central or midway position, that is, a position perpendicular to the caps i8and I9 where it Will not operate the follower stem ifi. Movementof the lever Hi to this position permits the spring 31 to move the valve 34 into seating engagement with its seat 35. Since the lever [B does not operate the plunger 46 the valve 55 remains seated as shown in Fig. 2-of the drawings.

With the valve 34 seated communicationlis out off between bore 36 and chamber 22 so that. circulation of oil from passage 33 to passage 2.3" is out off and with the valve 55 seated circulation of oil from chamber 50 to chamber 41' i'scut oil. Therefore as the pump continues to'operat'e, the pressure in the pump discharge pipe I'land connected passages 33 and 49 willincrease andlas' a consequence the pressure in the brake cylinder 9 will be increased to effect an application of the brakes.

It will be noted that when an application of the brakes is effected in the manner just described the self-lapping portion of the brakev controlling valve device is inoperative and the pressure in the pump discharge pipe and connected brake cylinder will be increased until such pressure is sufcifient to overcome the settingof the check valve spring l2. When this occurs the ball checkyalve'i ll will be unseated so that oil' discharged by the pump at a pressure above the setting of the: spring will be free to flow to the pump supply pipe f2,

by way of chamber 10, passage 23, and passage 42, to limit the brake cylinder pressure'toa predetermined degree.

When the circuit through the release coil' or winding 8! is closed following an' application of the brakes, of the type just described, the release coil or winding 8i is again energized. Upon en-" ergization of the coil or winding, the plunger'lfi and attached lever it are caused to'move'to' the position in which they are shown in thedrawings,

thereby unseating the valve 34 to efiect arelease of the brakes as hereinbefore described.

Having now described my invention, what. I

- claim as new and desire to secure-by Letters Patent, is: I

1. An electrically controlled brake COmpTlSlngl a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for normally circulatin a hydraulic medium through the system, abrake cylinder device, and a brake controllingivalve device operative at one time to impede'the'fiow of the hydraulic medium; through the system to efiect the operation of the brakeicylinderdevice to apply the brakes and operative at another time to permit the circulation of the hydraulic medium through the system to efiect the operation of the brake cylinder device to release the brake and electrical means under the control of an operator for effecting the operation of the brake controlling valve device, said electrical means comprising electroresponsive means operative when energized to effect operation of said brake controlling valve device to impede the flow of the hydraulic medium through the system and other electroresponsive means operative when energized to effect operation of said brake controlling valve device to permit the circulation of the hydraulic medium through the system. i

2. An electrically controlled brake comprising a hydraulic system for efiecting an application and a release of the brakes, said hydraulic system comprising a pump for normally circulating a hydraulic medium through the system, a brake cylinder device, and a brake controlling valve device operative at one time to impede the flow of the hydraulic medium through the system to effect the operation of the brake cylinder device to apply the brakes and operative at another time to permit the circulation of the hydraulic medium through the system to effect the operation of the brake cylinder device to release the brakes, a control lever pivotally mounted on said brake controlling valve device for controlling the operation of said brake controlling valve device; and electrical means under the control of an operator for effecting the operation of said control lever, said electrical means comprising electroresponsive means operative when energized to efiect movement of said lever in one direction to cause said brake controlling valve device to permit the free circulation of the hydraulic medium through the system and other electroresponsive means operative when energized to effect movement of said lever in a difierent direction to cause said brake controlling valve device to impede the fiow of the hydraulic medium through the system.

3. An electricall controlled brake comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for normally circulating a hydraulic medium through the system, a brake cylinder device, and a brake controlling valve device operative at one time to impede the flow of the hydraulic medium through the system to effeet the operation of the brake cylinder device to apply the brakes and operative at another time to permit the circulation of the hydraulic medium through the system to effect the operation of the brake cylinder device to release the brakes; electrical means for effecting the operation of said brake controlling valve device; said electrical means comprising electroresponsive means operative when energized to effect the operation of said brake controlling valve device to impede the flow of the hydraulic medium through the system and other electroresponsive means operative when energized to efiect operation of said brake controlling valve device to permit the circulation of the hydraulic medium through the system, and switch means under the control of an operator for effecting the operation of said electrical means.

4. An electrically controlled brake comprising a hydraulic system for eiTecting an application and a release of the brakes; said hydraulic system comprising a pump for normally circulating a hydraulic medium through the system, a brake cylinder device, valve means operative at one time to impede the flow of, the hydraulic medium through the system to effect the operation of the brake cylinder device to apply the brakes and operative at another time to permit the circulation of the hydraulic medium through the system to effect the operation of the brake cylinder device to release the brakes, pressure sensitive means operative for limiting the pressure of the hydraulic medium in the brake cylinder, and apparatus operative to control the operation of said valve means, said apparatus comprising electroresponsive means operative when energized to efiect the operation of said valve means to permit the flow of the hydraulic medium through the system and other electroresponsive means operative when energized to efiect the operation of said valve means to impede the flow of the hydraulic medium through the system and for at the same time exerting a pressure on said pressure sensitive means when an application of the brakes is being efiected, and said pressure sensitive means being subject to the opposing pressure of said other electroresponsive means and the brake applying hydraulic medium and being operative when the pressure of the hydraulic medium exceeds the opposing pressure of the other electroresponsive means for limiting the pressure of the hydraulic medium in the brake cylinder.

5. An electrically controlled brake comprising a hydraulic system for efiecting an application and a release of the brakes, said hydraulic system comprising a pump for normally circulating a hydraulic medium through the system, a brake cylinder device, and valve means operative at one time to impede the flow of the hydraulic medium through the system to effect the operation of the brake cylinder device to apply the brakes and operative at another time to permit the circulation of the hydraulic medium through the system to efiect the operation of the brake cylinder device to release the brakes; electrical means for controlling the operation of said valve means; said electrical means comprising electroresponsive means operative when energized to efiect the operation of said valv means to permit circulation of said hydraulic medium through the system and other electroresponsive means operative when energized to effect the operation of said valve means to impede the flow of the hydraulic medium through the system, means re- 'sponsive to opposing forces produced by the other electroresponsive means and the hydraulic medium in the brake cylinder for limiting the pressure in the brake cylinder; and means for varying the amount of current supplied to said other electroresponsive means and thereby the force of the other electroresponsive means, said electrical means being under control of an opera or.

6. An electrically controlled brake comprising a hydraulic system for efiecting an application and a release of the brakes, said hydraulic system comprising a pump for normally circulating controlling the operation of said valve means; 7

said electrical means comprising electroresponslve means operative when energized to efiect draulic medium in the brake cylinder for limiting the pressure in the brake cylinder, said means being operative when the force produced by t e hydraulic medium in th brake cylinder exceeds that of the other electroresponsive means to unseat said valve to provide for the discharge of' the hydraulic medium under pressure for limiting the pressure of the hydraulic medium in the brake cylinder; and means under control of an operator for varying the amount of current supplied to said other electroresponsive means and thereby the force of the other electroresponsive means.

'7'. A brake apparatus comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system, a brake cylinder, valve means having a release position for establishing a passage through which the-hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, and having an app ication position for closing off th flow of the hydraulic medium through said passage to the inlet end cf the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder, electroresponsive means operative when energized to retain said valve means in' its release position other electroresponsive means operative when energized to effect the operation of said valve means to its application position, and control means for energizing said other electrcresponsive means and for at the same time deenergizing said electroresponsive means.

8. A brake apparatus comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising apump for displacing the liquid in the system, a brake cylinder, valve means having a release position forestablishing a main passage through whichthe hydraulic medium freely flows from the discharge end ofthe pump back to the inlet end[ of the pump, a branch passage in open communication with said main passage at a point intermediate the discharg end of the pump and said valve means andleading to said brake cylinder device, said valve means having an application position for closing off the flow of the hydraulic medium through the said main passage to the inlet end of th pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, a control lever for normally maintaining said valve means in its release pcsition and operative for effecting the operation of the valve to its application position, and electrical means under the control of an operator for controlling said con.- trol lever, said electrical means comprising electroresponsive means operative when energized to effect operation of said lever for normally maintaining said valve means in the release position and another electroresponsive means operative when energized to eifectoperation of said lever for effecting the operation of said valve means to its application position.

of the brakes, said hydraulic system comprising, a pump for displacing the liquid in the system, a brake cylinder, valve means having a release position for establishing a main passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branch passage in open communication with said main passage at a point intermediate the discharge end of the pump and said valve means and leading to said brake cylinder device, said valve means having an application position for closing off the fiow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from thepump to said brake cylinder byway of'a portion of said main passage and said branch passage, and means for controlling said valve means; said 2) means comprising electromagnetic means for maintaining said valve in its release position andspring means for eifecting the operation of said valve means to an application position upon the failure of said electro-magnetic means tomaintain said valve in its release position.

a brake cylinder, valve means having a release 5 munication with said main passage at a point draulic medium through the said main passage intermediate the discharge end of the pump and said valve means and leading to said brake cylinder device, said valve means having an application position for closing off, the flow of the by to the inlet end of the pump to-provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, means normally maintaining said valve means in its release position and operative foreffectin'g the operation of the valve means to an' application position, a communication through which the" hydraulic medium may flow from the discharge end' of the pump back to the inlet end of the pump for by-passing said valve means in said main pas"- sage and other valve means for normally closing said communication and operative to open said communication upon a certain increase in the hydraulic pressure in the brake cylinder for limiting th hydraulic pressure in said brake cylinder to a predetermined degree.

11. A brake apparatus comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system, a brake cylinder, valve means having a release position for establishing a main passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branchpassage in open communication with said main passage at a point intermediate the discharge end of the pump andv said valve means and leading to said brake cyl inder device, said valve means. having an application position for closing off the flow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of'a'porfiion system for effecting an application and a releaseof said main passage and said branch passage, means normally maintaining said valve means in its release position and operative for effecting the o-perationof the valve means to an application position, a communication through which the hydraulic medium may flow from the discharg end of the pump back to the inlet end of the pump for lay-passing said valve means in said main passage, and a spring biased check valve device disposed in said communication for normally cutting off the flow of the hydraulic medium through said communication and operative upona certain increase in the pressure of the hydraulic medium in said brake cylinder for effecting operation of said check valve device to open said communication for limiting the pressure in the brake cylinder.

12, A brake apparatus comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system, a brake cylinder, valve means having a release position for establishing a main passage through I which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branch passage in open communication with said main passage at a point intermediate the discharge end of the pump and said valve means and leading to said brak cylinder device, said valve means having an application position for closing oil the flow of the hydraulic medium through the said main passage to the inlet end of the pump to provid for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, pressure limiting means for limiting the pressure of the hydraulic medium displaced by the brake cylinder, and means normally maintaining said valve means in its release position and operative for effecting the operation of the valve means to its application position and for conditioning said pressure limiting means for operation to limit the pressure of the hydraulic medium in the brake cylinder.

13. A brake apparatus comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system,

' abrake cylinder, valve means having a release position for establishing a main passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branch passage in open communication with said main passage at a point intermediate the discharge end of the pump and said valve means and leading to said brake cylinder device, said valve means having an application position for closing oil the flow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, pressure limiting means for limiting the pressure of the hydraulic medium displaced by the brake cylinder, and means normally maintaining said valve means in its release position and operative for effecting the operation of the valve means to its application position and for conditioning said pressure limiting means for operation to limit the pressure of the hydraulic medium in the brake cylinder, said last mentioned means comprising electro-magnetic means under control of an Operator.

-14. A brake apparatus comprising a hydraulic system for efiecting an application and a release of thebrakes, said hydraulic system comprising a pump for displacing the liquid in the system, a'brake cylinder, valve means having a release position for establishing a main passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branch passage in open communication with said main passage at a point intermediate the discharge end of the pump and said valve means and leading to said brake cylinder device, said valve means having an application position for closing off th flow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, pressure limiting means for limiting the pressure of the hydraulic medium displaced by the brake cylinder, and means normally maintaining said valve means in its release position and operative for eifecting the operation of the valve means to its application position and for conditioning said pressure limiting means for operation to limit the pressure of the hydraulic medium in the brake cylinder, said last mentioned means comprising electro-magnetic means for exerting pressure on said limiting means when energized, and electric resistance means variable under the control of an operator for efiecting variations in the pressure exerted by said electromagnetic means.

15. An electrically controlled brake comprising a hydraulic system for efiecting an application and a release of the brakes, said hydraulic system comprising a pump for normally circulating a hydraulic medium through the system, a brake cylinder device, and a brake controlling valve device operative at one time to impede the flow of the hydraulic medium through the system to efiect the operation of the brake cylinder device to apply the brakes and operative at another time to permit the circulation of the hydraulic medium through the system to effect the operation of the brake cylinder device to release the brakes; spring means for efiecting the operation of the controlling valve device to impede the flow of the hydraulic medium through the system, and electro-responsive holding means operative when energized to retain said controlling valve device, against the opposing pressure of said spring means, in the position to permit circulation of the hydraulic medium, a main holding circuit for normally energizing said holding means, and a switch interposed in said circuit operative upon the incapacitation of an operator to open said holding circuit for deenergizing said holding means.

16. An electrically controlled brake comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for normally circulating a hydraulic medium through the system, a brake cylinder device, and valve means operative at one time to impede the flow of the hydraulic medium through the system to effect the operation of the brake cylinder device to apply the brakes and operative at another time to permit the circulation of the hydraulic medium through the system to effect the operation of the brake cylinder device to release the brakes; spring means for effecting operation of the valve means to impede the flow of the hydraulic medium through the system; electroresponsive holding means operative whenenergized to retain said valve means in its position to permit circulation of the hydraulic medium; a holding circuit for normallyenergizing said holding means; a plurality of normally closed switches interposed in said holding circuit any one of which when open interrupts said holding circuit to cause deenergization of said holding means. a

17. A brake apparatus comprising a hydraulic system for efiecting an application and a re lease of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system, a brake cylinder, valve means having a release position for establishing a main passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branch passage in ope communication with saidmain passage at a point intermediate the discharge end of the pump and said valve means and leading, to said brake cylinder device, said valve means having an application position for closing off the flow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from. the pump to said. brake cylinder by way of a. portion of said main passage; and said branch passage, means for controlling said valve means, said means comprising electroresponsive means operative when energized to retain said valve means in its release position, other electroresponsive means operative when energized to permit movement of said valve means, to its application position, a release circuit for normally energizing said electro-responsive means, an application circuit through, which current may be supplied to energize said other electroresponsive means, and control means for energizing said application circuit and for deenergizing said release circuit. I o

18. A brake apparatus comprising a hydraulic system for efiecting an application and a release of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system, a brake cylinder, valve means having a release position for establishing a main passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branch passage in open communication with said main passage at a point intermediate the discharge end of the pump and said valve means and leading to said brake cylinder device, said valve means having an application position for closing off the flow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, means for controlling said valve means, said means comprising electro-responsive means operative when energized to retain said valve means in its release position, other electro-responsive means operative when energized to permit movement of said valve means to its application position, a release circuit for normally energizing said electro-responsive means, an application circuit through which current may be supplied to energize said other electro-responsive means, and control means for energizing said application circuit and for deenergizing said release circuit, and means responsive to the pressure of the hydraulic medium, established in the brake cylinder during braking for limiting the brake cylinder pressure to a predetermined degree.

19 A brakeapparatus comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic systemcomprising a pump for displacing the liquid in the system, a brake cylinder valve means havin a release position for establishing a main passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump, a branch passage n. open communication with said main passage at a point intermediate the dischargeend of the pump and said valve means and leading to said brake cylinder device, said valve means having an application position for closing off the flow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, electro-responsive means operative when energized to maintain said valve means in its release position, a normally closed circuit for energizing said electro-responsive means, a control switch interposed in said circuit and operative, in an applicationposition to open said circuit to deenergize said electro-responsive means, means operative in accordance with a track indicator for opening said circuit, means manually controlled independently of said control switch for opening said circuit, and means automatically operative in responseto opening of said circuit for effecting movement of said valve meansv to application position.

29. A brake apparatus comprising a hydraulic system for effecting an application and a release of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system, a brake cylinder, valve means having a release portion for establishing a main passage through which the hydraulic medium freelyflows from the discharge end of the pump back to the inlet end of the pump, a branch passage in open communication with said main passage at a point intermediate the discharge end of the pump and said valve means and leading to said brake cylinder device, said valve means having an application position for closing off the flow of the hydraulic medium through the said main passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder by way of a portion of said main passage and said branch passage, electro-responsive means operative when energized to maintain said valve means in release position, a normally closed circuit for energizing said electro-responsive means, a foot pedal, controlled switch interposed in said circuit and having a release position for closing said circuit and an application position for opening said circuit, a trip switch device interposed in said circuit and automatically controlled from the track for opening said circuit, a conductors switch device interposed in said circuit manually controlled from the vehicle for opening said circuit, and means automatically operative upon the opening of said circuit by either one of said switches for effecting movement of said valve means to its application position.

21. In a fluid pressure brake apparatus, in combination, a brake controlling valve device operative to one position for effecting an application of the brakes and operative to another position to effect the release of the brakes, electric means functioning upon its energization to maintain said brake controlling valve device in its brake releasing position, electric means functioning upon its energization and the denergization of the first mentioned electric means to actuate the brake controlling valve device to a brake application position to effect an increase in the degree of brake application, and means operative when both of said electric means are deenergized for actuating said brake controlling valve device to a second brake application position to effect an increase in the degree of brake application.

22. In a fluid pressure brake apparatus, in combination, a brake controlling valve device operative to one position for efiecting an application of the brakes and operative to another position to efiect the release of the brakes, electric means functioning upon its energization to maintain said brake controlling valve device in its brake releasing position, electric means functioning upon its energization and the deenergization of the first mentioned electric means to actuate the brake controlling valve device to a brake application position, means operative when both'of said electric means are deenergized for actuating said brake controlling valve device to a second brake application position, control means having a. normal position for effecting energization of said first mentioned electric means and deenergization of said second mentioned electric means and operative to a brake application position for effecting deenergization of said first mentioned electric means and energization of said second mentioned electric means, and means operative independently of said control means when said control means is in its said normal position for effecting deenergization of said first mentioned electric means.

23. In a fluid pressure brake apparatus, in combination, a brake controlling valve device operative to one position for effecting an application of the brakes and operative to another position to effect the release of the brakes, electric means comprising a first electroresponsive means and a second electroresponsive means, said electric means functioning upon energization of said first electroresponsive means and deenergization of said second electroresponsive means to maintain said brake controlling valve device in its brake releasing position and operative upon deenergization of said first and energization of said second electroresponsive means to actuate said brake controlling valve device to a brake application position, control means operative in an application position to effect energization of said second and deenergization of said first electroresponsive means, switch means controlled independently of said control means to efiect deenergization of said first electroresponsive means, and means operative when both said first and said second electroresponsive means are deenergized for actuating said brake controlling valve device to a second brake application position.

24. A brake apparatus comprising a hydraulic system for efiecting an application and a release of the brakes, said hydraulic system comprising a pump for displacing the liquid in the system, a brake cylinder, valve means having a release position for establishing a passage through which the hydraulic medium freely flows from the discharge end of the pump back to the inlet end of the pump and having an application position for closing off the flow of the hydraulic medium through said passage to the inlet end of the pump to provide for the displacement of the hydraulic medium from the pump to said brake cylinder, electroresponsive means operative when energized to retain said valve means in its release position, other electroresponsive means operative when energized to permit movement of said valve means to its application position, control means for effecting energization of said other electroresponsive means and for efiecting deenergization of said electroresponsive means, and means responsive to the pressure of the hydraulic medium established in the brake cylinder during braking for limiting the brake cylinder pressure to a predetermined degree.

EVERETT P. SEXTON.

CERTIFICATE OF CORRECTION.

Patent No. 2,5L i 9o2. March 21, 19th.

EVERETT P. SEXTON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 9, sec- 0nd column, line L l-1 2, claim 20, for the Word "portion" read. --position-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 26th day of September, A. D. 19bi Leslie Frazer (Seal) Acting Commissioner of Patents, 

